Introducing the new Mariner 2 Walnut

2 January 2014

We are pleased to repost this essay from Dr. Casey Kerrigan on treadmills. It originally appeared on the blog for OESH Shoes where Dr. Kerrigan is founder and chairman. Citing studies, she dispels one very popular myth that because “it’s a tiny bit easier to run on a treadmill, many will tell you that to make up for this difference you need to set the incline on your treadmill to 1%. But there’s no science out there to support that you have to.” She offers several other valuable tips, such as “progress slowly, increasing effort by no more than 10% each week.” One final note here: Kerrigan, who is 52 years old, usually logs 3 miles on the treadmill at a pace of somewhere between 8.0 and 8.5 miles per hour. –Bill Katovsky

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Tips for the Treadmill

by D. Casey Kerrigan, M.D.

Every year one of my New Year’s resolutions involves running. But I really don’t like running outside in January when it’s cold.

So, instead, I run on a treadmill as does our entire family. (That’s our daughter, Kellyn, in the photo). I’ve been enjoying running on a treadmill over the winters for more than a couple decades. In fact, to the chagrin of trainers and coaches who would advise otherwise, I once trained for a marathon, running exclusively on a treadmill. Yes, we could choose other forms of indoor aerobic exercise to get in shape. But colleagues of mine (also physical medicine and rehabilitation physicians) published this seminal research study in 1996 showing that the treadmill, compared to other forms of indoor exercise equipment (stationary bike, rowing machine Nordic Track, etc.), is the most efficient form of aerobic exercise. Specifically, they found that at the same level of perceived exertion, you burn more calories per minute on a treadmill than on any other type of indoor exercise equipment. A beautiful study, it has certainly guided our family’s routine.

Supported by the National Institutes of Health, I spent a great deal of time researching the biomechanics of treadmill walking and running. My research team and I published the definitive and most cited research studies here and here on the biomechanical similarities and differences between treadmill and overground walking and running, respectively. Our research has helped dispel pseudo scientific comments made about the treadmill such as “the treadmill belt propels you forward so that you do less work,” or “the treadmill belt pulls your leg through, resulting in a relatively passive extension of the hip, which reduces conditioning of the hip extensors.” Comments such as these often made by well meaning trainers and coaches are unfounded. Whether you’re moving over a stable base or the base is moving beneath you, the relative motion is the same, amounting to the same biomechanical conditions. Meaning that your hips, knees, etc. all move the same and that you’re working all the same muscles.

Now there are a couple differences between treadmill and overground running. The first is that in treadmill running, you don’t need to displace the air that is in front of you so that at a given speed it’s a tiny bit easier to run on a treadmill. Many will tell you that to make up for this difference you need to set the incline on your treadmill to 1%. But there’s no science out there to support that you have to. Granted there was this study that showed that running at a 1% incline takes the same amount of energy as running at the same speed outside on level ground outside. What many people don’t realize is that in that same study, there was no difference in energy between running outside and on a treadmill with 0% incline for speeds up to 7.5 miles per hour (equivalent to a 8 minute mile). In any event, if you feel like it’s easier to run on a treadmill, all you have to do, is increase the speed. If you end up running at a pace that’s faster than your usual outdoor pace on a level flat surface, just think of it as a needed winter confidence booster.

The second difference is that a treadmill offers a certain amount of compliance or springiness, which helps to reduce the peak forces through the joints and other injury sensitive areas of the body. The springiness that a treadmill provides is very different than the typical foam in a traditional cushioned running shoe sole that actually increases, rather than decreases, peak forces through joints, as we showed in this study here.

So, let’s proceed with a few tips beyond the usual “consult with your physician” “and “progress slowly, increasing effort by no more than 10% each week,” that applies to any form of exercise.

Don’t hold on to the handrail or console. Not only will you get less of a workout, holding on compromises your natural biomechanics. The handrails are there only to help you safely get on and off the treadmill. I’ve often been asked if it’s okay to hold on if you have an injury in your leg or foot. My answer to that is “no.” It’s very difficult, if not impossible, to unweight yourself at just the right time that would avoid placing undue stress somewhere else in the body. Believe me (and our research) that it would have to take a sophisticated computerized feedback-controlled unweighting device to correctly unweight oneself during walking or running.

Set the treadmill to “Manual.” That is, don’t fuss with the fancy programs that are often available on a treadmill. This gives you more control in how much you push yourself. Basically, you want to listen to your body (as you would when running or walking outside), not the machine.

Set the incline to 0% and don’t be compelled to increase it unless you would like to. Personally, I never use incline on a treadmill. Mainly because it confuses me as to how hard I’m actually working. But also because of this seminal study here that we did showing that there are no clinically significant biomechanical differences between running on a moderate incline, level, or decline treadmill surface. That is, the peak stresses on your knees and your other joints are the same whether you run on an incline or not. Moreover, incline is an added variable that seems to be very inconsistent between different treadmills. The reason for the variability lies in how the treadmill is mechanically jacked and supported when in an incline position. Depending on the quality of the treadmill, the incline mechanism affects the stiffness of the treadmill surface and can sometimes introduce vibrations, which makes things even more confusing. I like to know exactly how much work I’m doing. And altering just the speed allows me that opportunity.

Running on a treadmill offers an easy opportunity to figure out your stride cadence, that is, the number of strides you take each minute. A stride is the interval between when one foot touches the ground and when that same foot touches the ground again. A stride encompasses two steps with a step being defined as the interval between when one foot touches the ground and when the other foot touches the ground.

All you need to do to determine your stride cadence is count how many times the same foot touches the ground in one minute. Your stride cadence should be 90 or above. If it’s any less than that, you’re overstriding. That is, you’re taking longer strides than what’s physiologically normal. Overstriding imposes excessive forces through your joints, bones, and tendons. Bottomline, you don’t want to overstride, but understand that most people accustomed to running in traditional cushioned running shoes, unfortunately do. Traditional running shoes cause an unnaturally long stride that imposes excessive forces through joints, bones and tendons. (Wearing OESH that are perfectly flat from the heel to the toe can get your stride and your cadence where they should be.) You can also try using a metronome to improve your cadence.

Listen to music! Listening to songs that have a good strong beat (think Rock ‘n Roll!) has been nicely shown in this study to improve motivation. While I strongly discourage listening to music while running outside on the streets (headphones make you oblivious to cars, bicycles, and other potential dangers), I’m all for cranking it up when on the treadmill. As long as you refrain from trying to actually dance while running, you should be safe. I keep about 50 songs that I especially like in an iTunes library called “Running” and play them in sequence, picking up from where the sequence left off the workout before. I edit the library from time to time but some of those ‘80’s hits that have a good strong beat, have managed to hang on for quite awhile.

Don’t be afraid to explore other things that may motivate you. Science will catch up in demonstrating that certain things are better than others in keeping people motivated. But in the meantime, you can experiment on yourself. For example, you might like watching TV. I’ve never liked watching TV at the gym (even when it’s built-in to the treadmill – I find it too distracting) but this year, for {my husband} Bob’s birthday, we got him a projection screen TV that sits in the vicinity of our home treadmill. The TV is perpetually set to Bob’s NFL football station but I found that if I go up just one station I get a channel called “Create” that has things like cooking, traveling, and home repair projects. I don’t listen to the sound, just watch, which is the perfect amount of distraction, for me at least, while running.

I don’t like keeping constant track of how far or how many minutes I’ve gone while I’m actually running so I either keep my eyes off the reading on the console, throw my towel over it, or change the reading so that some other parameter is front and center. Of course I do check now and again as the last thing I want to do is run a hundredth of a mile more than I set out to run.

That’s it. Running on a treadmill is a great way to either get into or stay in shape during the winter. It’s so great in fact that you may find you like running on a treadmill year-round. That is perfectly reasonable and I know many people who do that. But personally I feel if I ran on a treadmill year-round I’d lose some of the excitement of running on it during the winter… sort of like setting up the Christmas tree in June. But that’s just me.

Comments (7)

Great article! Thanks for posting. One of the things I do to help with the boredom (in addition to listening to music): I know very well 3, 4, 5 and 6 mile routes that I run over the road. When I'm on the treadmill I really imagine myself being at that spot in the route that corresponds to where I would be were I running outside. "I'm at mile 2.5 - that's that particular intersection." By doing this I've been able to keep myself focused on how much more I have based on real routes - and not just watching the numbers tick by.

As much as I love jogging, trail running is the best. Very relexing and I always enjoyed my morning running. Anyways, I like your blog post and share it with my friends. Will come back to read more here. Thanks.

I would really like further clarification about how it is possible that treadmill running is biomechanically the same as running on the ground. The belt carries your leg behind you, so how can you possibly have the same use of your gluteus muscles to drive the leg into extension?
Thank you for any replies and discussion.

That treadmill running is essentially the same biomechanically as running on the ground is supported by the biomechanics studies we did which you can link to in my original post here at http://oeshshoes.com/2014/01/my-scientific-personal-advice-for-treadmill-training/. Although it may seem like it would, the belt truly doesn't carry the leg into extension any more than the ground itself pulls the leg into extension.

Thanks for this article. It was just the motivation I needed in this cold, wet NYC winter. I am now running on the treadmill when weather doesn't allow me to run outdoors, and I'm surprised at how much I enjoy it. I had convinced myself, after a year of rehabbing my surgically repaired knee on the treadmill, that I hated it. Not at all! In fact, I've figured out some important but subtle adjustments to my form and my pace while on the treadmill. I'll take them outdoors with me when the weather warms up again.

Very nice article describing the bio-mechanical workouts of the treadmill. As a gym goer, i just loved to workout with treadmill as physicians say it is the best cardio vascular exercise that never gives multiple benefits in just a run!